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Proceedings Paper

Methylene blue solder re-absorption in microvascular anastomoses
Author(s): Jeremy F. Birch; J. Hepplewhite; Malcolm Frier; Peter R. F. Bell
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Paper Abstract

Soldered vascular anastomoses have been reported using several chromophores but little is known of the optimal conditions for microvascular anastomosis. There are some indications of the optimal protein contents of a solder, and the effects of methylene blue on anastomotic strength. The effects of varying laser power density in vivo have also been described, showing a high rate of thrombosis with laser power over 22.9Wcm-2. However no evidence exists to describe how long the solder remains at the site of the anastomosis. Oz et al reported that the fibrin used in their study had been almost completely removed by 90 days but without objective evidence of solder removal. In order to address the issue of solder re-absorption from the site of an anastomosis we used radio-labelled albumin (I-125) incorporated into methylene blue based solder. This was investigated in both the situation of the patent and thrombosed anastomosis with anastomoses formed at high and low power. Iodine-125 (half life: 60.2 days) was covalently bonded to porcine albumin and mixed with the solder solution. Radio-iodine has been used over many years to determine protein turnover using either I-125 or I-131. Iodine-125 labelled human albumin is regularly used as a radiopharmaceutical tool for the determination of plasma volume. Radio-iodine has the advantages of not affecting protein metabolism and the label is rapidly excreted after metabolic breakdown. Labelling with chromium (Cr-51) causes protein denaturation and is lost from the protein with time. Labelled albumin has been reported in human studies over a 21-day period, with similar results reported by Matthews. Most significantly McFarlane reported a different rate of catabolism of I-131 and I-125 over a 22-day period. The conclusion from this is that the rate of iodine clearance is a good indicator of protein catabolism. In parallel with the surgery a series of blank standards were prepared with a known mass of solder to correct for isotope decay and allow data interpretation in terms of the actual amount of the solder remaining after a particular time. The anastomoses were formed with a known amount of solder and allowed to continue for up to 60 days before being sacrificed. The explanted vessels were then placed into a gamma counter and the amount of solder remaining expressed as a percentage. In this way the proportion of albumin left at the site of the anastomosis could be determined. By changing the power density of the laser it has been shown that the patency of soldered microvascular anastomoses is altered. By doing this it was hoped to determine any effect thrombosis might have on solder re-absorption. In addition the explanted vessels were inspected for inflammation, patency and aneurysm formation.

Paper Details

Date Published: 12 September 2003
PDF: 12 pages
Proc. SPIE 4949, Lasers in Surgery: Advanced Characterization, Therapeutics, and Systems XIII, (12 September 2003); doi: 10.1117/12.478326
Show Author Affiliations
Jeremy F. Birch, Salisbury District Hospital (United Kingdom)
J. Hepplewhite, Leicester Royal Infirmary (United Kingdom)
Malcolm Frier, Nottingham Univ. Hospital (United Kingdom)
Peter R. F. Bell, Univ. of Leicester (United Kingdom)

Published in SPIE Proceedings Vol. 4949:
Lasers in Surgery: Advanced Characterization, Therapeutics, and Systems XIII
Eugene A. Trowers; Timothy A. Woodward; Werner T.W. de Riese; Lawrence S. Bass; Nikiforos Kollias; Udayan K. Shah; Brian Jet-Fei Wong; Reza S. Malek; David S. Robinson; Hans-Dieter Reidenbach; Keith D. Paulsen; Kenton W. Gregory; Lawrence S. Bass; Abraham Katzir, Editor(s)

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